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Answer the following. (Class 12 Biology 2025, Q31B)

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BiologyCBSE Class 12 · Board exam 2025, set 57/1/1 · 5 marks · Long answer

CBSE Class 12 Biology 2025: question 31(B)

Set in the CBSE Class 12 board exam of 2025, paper 57/1/1, section E, question 31(B), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q31(B) · 5 marks · Long answerMicrobes in Human Welfare

Answer the following.

  1. (i)

    Study the following table & fill 'H', 'I', 'J', 'K', 'L' and 'M' in following table with suitable words :

    Chemical / Bioactive MoleculeMicro-organismCategoryUse
    (a)Butyric acidHIImportant applications in food, chemical & pharma industry
    (b)JMonoscus purpureusKInhibit cholesterol biosynthesis pathway
    (c)Cyclosporin ALFungusM
    0 marks
  2. (ii)

    Why are baculoviruses used as biological control agents ?

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 57/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Recall the NCERT table of bioactive molecules from 'Microbes in Human Welfare'.

Hint 2

Cyclosporin A is given to organ-transplant patients. What does it do to their immunity?

Hint 3

Why would a pest-control agent that attacks only one target be preferred?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (i)(a) H = Clostridium butylicum

    ½ mark

  2. I = Bacterium

    ½ mark

  3. (b) J = Statins

    ½ mark

  4. K = Yeast (fungus)

    ½ mark

  5. (c) L = Trichoderma polysporum

    ½ mark

  6. M = Immunosuppressive agent, used in patients who have undergone organ transplantation

    ½ mark

  7. (ii) Reasons baculoviruses are used as biocontrol agents:
    1. They are species-specific and have narrow-spectrum insecticidal action, attacking only the target insects and arthropods (e.g. Nucleopolyhedrovirus).
    2. They have no negative impact on non-target organisms such as plants, mammals, birds, fish and beneficial insects, so they are ideal in IPM and ecologically sensitive areas.

    2 marks

Answer: (i) H = Clostridium butylicum, I = bacterium, J = statins, K = yeast/fungus, L = Trichoderma polysporum, M = immunosuppressant in organ transplant patients; (ii) species-specific, narrow-spectrum action with no harm to non-target organisms.

Where the marks are

  • H: Clostridium butylicum (½ mark)
  • I: bacterium (½ mark)
  • J: statins (½ mark)
  • K: yeast/fungus (½ mark)
  • L: Trichoderma polysporum (½ mark)
  • M: immunosuppressant (½ mark)
  • Two reasons for using baculoviruses, e.g. species-specific/narrow spectrum and no harm to non-target organisms (1 + 1 marks)

Revise the chapter

Practise this chapterBoard-style questions from Microbes in Human Welfare, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 57/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.